WO2015068871A1

WO2015068871A1 - Device for preventing overcharge of battery cell for secondary battery

Info

Publication number: WO2015068871A1
Application number: PCT/KR2013/010122
Authority: WO
Inventors: 이지석
Original assignee: 에스케이이노베이션 주식회사
Priority date: 2013-11-08
Filing date: 2013-11-08
Publication date: 2015-05-14

Abstract

The present invention relates to a device for preventing overcharge of a secondary battery and, more particularly, to a device for preventing overcharge of a battery cell for a secondary battery, the device physically detecting an expansion of a battery cell without power supply and shutting off charge power when the battery cell is overcharged.

Description

Overcharge prevention device for secondary battery

The present invention relates to an overcharge preventing device for a secondary battery, and more particularly, to an overcharge preventing device for a secondary battery battery cell that blocks charging power by physically detecting the expansion of the battery cell without power supply when the battery cell is overcharged.

In general, secondary batteries are rechargeable and have a large capacity, such as nickel cadmium, nickel hydrogen, and lithium ion batteries. Among them, the lithium ion battery has attracted attention as a next generation power source due to its excellent characteristics such as long life and high capacity. However, when the lithium ion battery is exposed to an abnormal use environment such as overcharging, short circuit, reverse connection, and heat exposure, gas due to electrochemical action is generated inside the battery, thereby increasing the battery internal pressure. Increasing the internal pressure of the battery causes the battery to expand and in particular, if abnormal use time such as overcharging continues, the electrolyte or the active material is partially decomposed, and the internal pressure and temperature of the battery may rise rapidly, causing an explosion or fire.

For the above reasons, in order to verify the safety of the secondary battery, various thermal stability tests such as high temperature storage test, thermal shock test, and heat exposure test, as well as tests of overcharge, overdischarge, short circuit, reverse connection, etc., are conducted. Under these thermal safety test conditions, there should be no explosion or ignition of the battery.

At present, various attempts have been made to improve the safety of secondary batteries, and discharge the gas generated inside the secondary battery through the rupture portion of the battery case or directly cut off the battery circuit using the rupture disk inside the battery. How to do is known. In this case, when gas is generated in the situation such as overcharge and the internal pressure exceeds the design value, the sealing part is ruptured or the battery power is cut off. There is a problem that causes.

In order to solve the above problems, a device for detecting an overcharge of the battery and blocking the charging power through the battery management system (BMS) has been known, but the battery management system (BMS) malfunctions, or the battery management system (BMS) If the power is not supplied, an additional problem arises in that an overcharge protection effect cannot be expected.

The present invention has been made to solve the above problems, an object of the present invention is to provide a sensing unit short-circuited by the expansion of the battery cell, by connecting the sensing unit in parallel to the charging and discharging line in charge of the expansion of the battery cell The present invention provides an overcharge preventing device for a secondary battery battery cell, which short-circuits a discharge line and induces disconnection of a charge / discharge line to block charging power supplied to the battery cell.

In particular, a current concentration section is formed on the charge / discharge line when the charge / discharge line is short-circuited, and disconnection is made in the current concentration section, thereby providing an overcharge preventing device for the secondary battery battery cell that can arbitrarily set the disconnection section of the charge / discharge line. have.

The overcharge preventing device of the present invention, at least one or more battery cells, and the overcharge preventing device of a secondary battery battery cell comprising a charge and discharge line for charging and discharging the battery cell, the overcharge preventing device, the battery cell A detector disposed adjacent to and short-circuited when the battery cell is expanded beyond a predetermined thickness; Includes, the sensing unit is connected in parallel on the charge and discharge line.

In this case, the sensing unit, a conductive material, the first sensing member connected to the anode line of the charge and discharge line; And a second sensing member disposed to be spaced apart from the first sensing member at a predetermined distance and connected to the cathode line of the charge / discharge line using a conductive material. The first sensing member or the second sensing member is shorted in contact with the other of the first sensing member or the second sensing member by interlocking when the battery cell is expanded.

In addition, on the charge and discharge line, the disconnection unit is disconnected when the detection unit short-circuited; Is provided, the disconnection portion is formed thinner than the average thickness of the charge and discharge line.

In another embodiment, the disconnection part includes an electrode tab of the battery cell.

In another embodiment, the disconnection part is made of a material having a low melting point so as to be disconnected by heat during disconnection of the charge / discharge line.

The overcharge preventing device of the secondary battery battery cell of the present invention having the above configuration is easy to secure the space inside the secondary battery because the size of the sensing unit for detecting the expansion of the battery is easy, there is an excellent space utilization.

In addition, the detection unit does not need a separate power supply, there is no fear of malfunction, and unless a mechanical defect occurs, effectively detecting an overcharge of the battery cell, thereby blocking the charging power, thereby preventing an accident due to battery overcharge.

In addition, it is possible to induce a disconnection in a relatively safe section without fear of ignition or explosion on the charge and discharge line has the effect of preventing secondary accidents due to disconnection of the charge and discharge line.

1A is a battery cell perspective view

1B is a schematic side view of a battery cell

1C is a schematic side view of the battery cell when inflated

2 is a side view of the overcharge preventing device of the present invention

3 is a cross-sectional view of the overcharge preventing device of the present invention

Figure 4 is an operating state of the overcharge prevention device of the present invention (normal)

5 is an operation state diagram of the overcharge preventing device of the present invention (overcharge)

10 sensing unit 11 first sensing member

12 second sensing member 13 case

20: battery cell 30: disconnection part

CL: charge / discharge line CL1: anode line

CL2: cathode line

The present invention focuses on the fact that the battery cell expands during overcharging, and short-circuits the sensing unit through the expansion load of the battery cell, and connects the sensing unit in parallel to the charging / discharging line, thereby disconnecting the charging / discharging line of the battery cell by short-circuiting the sensing unit. It is to provide an overcharge preventing device that prevents charging from proceeding any further. At this time, since the sensing unit is operated in conjunction with the physical load, there is an advantage that the possibility of malfunction is rare unless a mechanical defect such as an impact or damage is not generated, without a power source. In addition, since it can be implemented in a simple configuration, it is easy to secure space and has an excellent space utilization.

Hereinafter, an embodiment of the overcharge preventing device of the present invention as described above will be described in detail with reference to the accompanying drawings.

Referring to Figure 1a, the battery cell 20 applied to the overcharge protection device according to an embodiment of the present invention is made of a sealed structure. Normally, as shown in FIG. 1B, the battery cell 20 has a constant thickness. When the battery cell 20 is placed in an excessive state such as overcharge, short circuit, reverse connection, heat exposure due to the nature of the sealed structure, gas is generated inside the battery cell 20 and expands as shown in FIG. 1C, and expansion is performed. If continued, the battery cell 20 may ignite and explode when chemicals such as electrolytes are leaked or the degree is severe.

Referring to FIG. 2, the overcharge preventing apparatus according to an exemplary embodiment of the present invention includes a sensing unit 10 installed adjacent to a side of a battery cell 20 in which a plurality of stacked cells are stacked. The detector 10 detects the expansion of the battery cell 20 adjacent to the side of the battery cell 20.

Referring to FIG. 3, the sensing unit 10 according to an exemplary embodiment of the present invention may include a first sensing member 11 made of a conductive material, a conductive material, and spaced apart from the first sensing member 11 by a predetermined distance. The second sensing member 12, the first sensing member 11, and the second sensing member 12 may include a case 13 accommodated therein. The first sensing member 11 has a plate shape having a predetermined length and width, and is fixedly installed in the case 13. The second sensing member 12 may have a plate shape having a predetermined length and width, spaced apart from the first sensing member 11 by a predetermined distance, and installed adjacent to the side surface of the battery cell 20. The second sensing member 12 is preferably disposed to contact the first sensing member 11 by the expansion pressure when the battery cell 20 is inflated, and the first sensing member 11 and the second sensing member 12 are When contacted is configured to short-circuit each other. The separation distance between the first sensing member 11 and the second sensing member 12 may be adjusted according to the size and capacity of the battery cell 20. That is, when the expansion displacement of the battery cell 20 is large, the separation distance between the first sensing member 11 and the second sensing member 12 is long, and when the expansion displacement of the battery cell 20 is small, the first sensing member 11 is small. The separation distance between the second sensing member 12 may be configured to be short.

As long as the first sensing member 11 and the second sensing member 12 can be shorted in contact with each other by the expansion of the battery cell 20 in addition to the above-described configuration, any shape may be applied.

The case 13 has a space formed therein and has a housing shape having an open surface formed on one surface thereof. The case 13 has a space formed therein to accommodate the first sensing member 11 and the second sensing member 12 spaced apart by a predetermined distance therein, and the opening surface is installed to be in contact with the side surface of the battery cell 20. Can be. Therefore, the overcharge preventing device of the present invention is excellent in space utilization because it can be installed if only the space that can be fixed to the case 13, there is an advantage that there is no restriction in the installation position.

4 and 5, the overcharge preventing apparatus according to an embodiment of the present invention further includes a charge / discharge line CL and a disconnection part 30. The charge / discharge line CL may be supplied with external power to charge the battery cell 20, and a general high voltage line for discharging power of the battery cell 20 may be applied to a device requiring a power source. The charge / discharge line CL is composed of an anode line CL1 and a cathode line CL2. The first sensing member 11 is electrically connected to the anode line CL1, and the second sensing member 12 is electrically connected to the cathode line CL2. When the first sensing member 11 and the second sensing member 12 are shorted in contact with each other by the above configuration, an overcurrent flows on the charge / discharge line CL, and a relatively weak portion on the charge / discharge line CL is generated. Is disconnected to stop charging or discharging the battery cell 20. At this time, the disconnection portion 30 is provided to arbitrarily designate the disconnection portion of the charge / discharge line CL. The disconnection part 30 may be formed on the charge / discharge line CL and may be made of a material having a low melting point to facilitate disconnection when high heat is generated due to overcurrent. The disconnection unit 30 may be applied to a separate member or to an electrode tab that is a component of the battery cell 20. In another embodiment, the disconnection part 30 may be formed to have a thickness smaller than the average thickness of the charge / discharge line CL. This is to induce a disconnection in the disconnection unit 30 when an overcurrent is applied by reducing the resistance of the disconnection unit 30 to the charge / discharge line CL. The disconnection unit 30 may be disposed at a safe point where explosion or ignition does not occur on the secondary battery during disconnection, thereby preventing secondary accidents due to disconnection of the charge / discharge line CL.

Hereinafter, the operation of the overcharge protection device according to an embodiment of the present invention configured as described above will be described with reference to the drawings.

Referring to FIG. 4, in the overcharge preventing apparatus according to an embodiment of the present invention, the first sensing member 11 and the second sensing member 12 are spaced apart at a predetermined distance during normal operation of the battery cell 20 to charge and discharge the battery. It is configured to have no influence on the charging or discharging of the line CL.

Referring to FIG. 5, in the overcharge preventing apparatus of the present invention, when the battery cell 20 is overcharged and expanded, the first sensing member 11 and the second sensing member 12 are shorted to contact each other, and the first sensing member ( 11) and the second sensing member 12 short-circuit the charge-discharge line (CL) connected in parallel so that the overcurrent is applied on the charge-discharge line (CL). The charge / discharge line CL is overheated due to the overcurrent application, and the short circuit 30 provided on the charge / discharge line CL is disconnected due to overheating, thereby disconnecting the charge / discharge line CL. As the charge / discharge line CL is disconnected, the charging or discharging of the battery cell 20 does not proceed, and further damage due to the expansion of the battery cell 20, for example, ignition due to gas leakage inside the battery cell 20. And explosion accidents. In particular, the short circuit unit 30 may be disposed in any section on the charge / discharge line CL, and thus, the short circuit unit 30 may be disposed in a section where the risk of ignition and explosion on the secondary battery may be caused by disconnection of the charge / discharge line CL. Secondary accidents can be prevented beforehand.

The technical spirit should not be interpreted as being limited to the above embodiments of the present invention. Various modifications may be made at the level of those skilled in the art without departing from the spirit of the invention as claimed in the claims. Therefore, such improvements and modifications fall within the protection scope of the present invention as long as it will be apparent to those skilled in the art.

Claims

An overcharge preventing device for a secondary battery battery cell including at least one battery cell and a charge / discharge line for charging and discharging the battery cell.

The overcharge preventing device,

A detector disposed adjacent to the battery cell and short-circuited when the battery cell is expanded to a predetermined thickness or more; Including;

The sensing unit is connected to the charge and discharge line in parallel, the overcharge preventing device of a secondary battery battery cell.
The method of claim 1,

The detection unit,

A first sensing member made of a conductive material and connected to the anode line of the charge / discharge line; And

A second sensing member disposed to be spaced apart from the first sensing member at a predetermined distance and connected to the cathode line of the charge / discharge line with a conductive material; Consists of,

Any one of the first sensing member or the second sensing member is in contact with the other one of the first sensing member or the second sensing member in a short circuit in conjunction with the expansion of the battery cell, overcharge preventing device for a secondary battery battery cell.
The method of claim 1,

On the charge and discharge line,

A disconnection unit disconnected when the sensing unit is shorted; Is provided, the overcharge preventing device of the secondary battery battery cell.
The method of claim 3, wherein

The disconnection unit,

It is formed thinner than the average thickness of the charge and discharge line, the overcharge preventing device of a secondary battery battery cell.
The method of claim 3, wherein

The disconnection unit,

Overcharge preventing device of a battery cell for secondary batteries, which is an electrode tab of the battery cell.
The method of claim 3, wherein

The disconnection unit,

An overcharge preventing device for a secondary battery battery cell, which is made of a material having a low melting point so as to be disconnected by heat during disconnection of the charge / discharge line.